Circuit interrupter



Oct 28, 1941. R. c. VAN slcKLE ETAL CIRCUIT NTERRUPTER Patented Oct. 28, 1941 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTEB,

Roswell C. Van Sickle, Wilkinsbnrg, and Erik H.

Hall, Turtle Creek, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application september 19,1939, serial No. 295,578

(ci. zoo-145) 21 Claims.

This invention relates to circuit interrupters, and more particularly to contact structures therefor.

In the application oftB. P. Baker, Serial No. 230,946, led September 21, 1938, and issued August 19, 1941, as Patent No. 2,253,009, and assigned to the assignee of the instant application is shown and described a high-voltage high-power circuit interrupter of the liquid immersed type employing a relatively small quantity of arc extinguishing liquid. The contact structure of the breaker described in the aforesaid application constitutes a stationary contact means and a movable contact coacting therewith to establish an arc within an arc chamber immersed in the are extinguishing liquid. The movable contact is carried by an operating member movable a predetermined distance through the arc chamber byran operating spring.

The operating member is formed in part of conducting material and constitutes a portion of the conducting circuit through the interrupter. In addition to the provision of a circuit interrupting break within the arc chamber, the contact structure is so arranged that an isolating break is provided in the circuit exteriorly of the arc chamber. This isolating break occurs between two separable sections of the conducting portion of the operating member. The operating mechanism for closing the breaker directly engages the free section of the operating member so that during the closing operation, the two conducting sections of the operating member are initially brought into engagement so as to close the isolating break. The operating member is then moved as a unit to close the interrupting break within the arc extinguishing chamber.

Modern circuit breaker practice demands high A further object of the invention is to provide a contact structure, for circuit interrupters arranged to insert in the connected circuit in sequence, an interrupting break and an isolating break and which structure :further provides for limited relative movement of the contact members between which the isolating break is ultimately formed while maintaining a high pressure low resistance contact between the contact members.

Another object of our invention resides in the provision of separable contact members for a circuit interrupter having coacting elements for cushioning the shock resulting from forceful engagement of the contact members during the closing operation of the interrupter.

Still another object of our invention is the provision of separable contact members for highvoltage, high-power circuit interrupters which are simple in construction, rugged in design, shock-proof in closing and which when in the open circuit position present a smooth contour' free from sharp projections so as to more evenly distribute the electrostatic stress to enable the gap formed therebetween to withstand high voltage.

Other objects and advantages will be apparent from the following description when taken in connection with the accompanying drawing, in

which:

Figure 1 is a sectional View showing the interrupter of our invention;

Fig. 2 is an enlarged fragmentary sectional view showing the separable contact members of the contact structure in the closed circuit position, and l Fig. 3 is a sectional view of the contact mem- A bers of Fig. 2 showing the contact members disspeed closure as well as high speed in clearing a fault. In order to obtain high speed closure, the operating mechanism is usually designed to impart high speed movement to the contacts during the initial closing movement, when the requisite closing force is relatively low and to decrease the speed of contact movement during the latter part of the closing stroke when the required closing force is high.

We have discovered that an attempt to obtain high speed closure with asimple contact structure, as shown in the aforesaid application, resulted in injury to the operating mechanism as Well as the contact structure occasioned by the impact of the two separable sections forming the isolating break.

The main object of our invention, therefore, is tc provide a contact structure tor circuit interrupters of the aforesaid type which permits high speed closure ci the interrupter without injury to the operating mechanism or the contact structure.,

engaged from each other and in the partially open circuit position.

Referring to the drawing, the reference numeral 5 designates the upper end of a metallic casing forming part of the circuit interrupter housing. Disposed on top of the casing 5 is a tubular housing comprising an outer insulator 'l of Weatherproof material and an inner tubular member 9 of insulating material which is rigidly secured to the casing 5 and maintains the outer tubular member l in compression, against the casing 5.l

2| and 23 are a plurality of spaced washers 25 of insulating material which form an arc extinguishing chamber 26.

The circuit interrupting unit |3 is provided with a centrally positioned operating member 21 extending therethrough having a metallic upper portion 29 extending exteriorly thereof and another metallic portion 3| at the lower end thereof, a portion of which also extends exteriorly of the chamber 2G. The two metallic portions 29 and 3| are joined by an insulating section 33, the

outer surface of which is corrugated and adapted to be moved into the arc chamber 26. The lower metallic portion 3| is composed of two separable conducting sections 35 and 31. The upper section 35 is provided with a ring contact 39 which cooperates with the contact fingers 2| and 33. The casing i1 of the interrupting unit |3 is connected by conductor 4| to a line terminal 43. A flexible conductor 45 joins the movable contact section 31 with a second line terminal 41. Thus the electrical connection through the interrupter proceeds from the terminal 43, conductor 4l casing i1, contact support I9, contacts 2|, 23, 39, conducting sections 35, 31 through the flexible conductor 45 to the terminal 41.

The casing I1 has a plurality of upstanding guide rods 4S, the upper ends of which support a pressure plate 48. Secured to the upper section 29 of the operating member 21 and yslidably operative with respect to the guide rods 46 is a pressure plate 49. A plurality of springs 5| disposed between the pressure plates 48 and 49 coact so as to move the operating member 21 to the open circuit position. Movement of the operating member 21 is controlled by an operating mechanism generally indicated at 53 disposed within the casing 5. preferably of the type shown and described in the aforesaid Baker application and makes pivotal engagement with the contact member 31 at 55 and provides for substantially straight line movement of the operating member 21 through the interrupting element l1. Operation of the interrupter is as follows.

Upon the occurrence of an overload, a suitable trip mechanism, not shown, causes the operating mechanism 53 to release the operating member 21 so as to permit the `operating springs 5| to move the operating member 21 downwardly. During the downward movement of the operating member 21, an arc is drawn between the contact nger 2'3 and the contact ring 39 and as the contact ring 39 moves into the arc chamber 25, the arc is quickly extinguished in accordance with the theory more fully set forth in the aforesaid Baker application. Y

As the contact ring 39 reaches the lower end of the casing l5, its motion is arrested with a dashpot action as the result of the bottom of plate 49 coming against the flat top of casing |1. The operating mechanism 53, however, continues to move to the open circuit position, carrying with it the lower conducting section 31, thereby causing the section 31 to separate from the section 35 to establish an isolating break below the casing I5 within the tubular strain member 9. Travel of the conducting section 31 to the open circuit position is limited by a suitable stop 40 positioned in the path of movement of the section as shown.

In order to provide a high pressure low resistance contact between the sections 35 and 31 when the interrupter is in the closed circuit position, and also during the circuit interrupting operation, a contact arrangement is provided as The operating mechanism 53 is` more clearly shown in Figs. 2 and 3. The section 35 has an annular recess 51 and a centrally projecting stem 59 at its lower end thereof.

The recess 51 provides a downwardly extending flange 6|, the inner and outer edges of which are slightly tapered as shown. The inner surface of the flange 6| has an annular groove 63 therein for the reception of a plurality of contact fingers 65. The contact ilngers $5 are disposed in circumferentially spaced relation about the stem 59 and have a lateral projection 61 extending into the groove 63. The contact iingers 65 are maintained in their spaced relation with respect to each other by a radially slotted washer 69 secured to a sleeve 1l surrounding the stem 59. The sleeve 1| i5 held upon the stem 59 by a cap member 13 screw threaded to the lower end of the stem. The sleeve 1| is of such length that when the cap member 13 is drawn up iirmly against the stem 59, the sleeve is still free to rotate upon the stem. The cap member 13 has a slight upstanding flange 15 which serves as a stop member forl the lower ends of the contact fingers 65 to limit the outward pivotal movement of the contact fingers. Each of the contact fingers 65 is biased outwardly by a pair of coil springs 11, the inner ends of which pass through suitable apertures in the sleeve 1| and bear against the stem 59. The outer ends of the springs 11 are recessed in suitable slots provided in the contactl fingers 65 as shown.

The upper end of the contact section 31 is provided with a cup-shaped portion 19 into which the contact fingers 65 and the cap portion 13 extend when the two sections 35 and 31 are in engagement. As clearly shown in Fig. 2, the biasing springs 11 urge the contact lingers 65 outwardly so that the ends of the fingers are respectively maintained in high pressure engagement with the inner surfaces of the hollow portions 51 and 19. In other words, the contact fingers 65 serve as bridging members electrically connecting the two contactl sections 35 and 31 without the use of nexible shunts usually employed in structures of the prior art. When the interrupter is in the closed circuit position a high pressure butt type contact is maintained between the cap member 13 and the bottom of the cup-shaped portion 19 in addition to the contact provided by the ccntact fingers 65.

As more clearly shown in Figs. 2 and 3, it will be noted that the portion 19 of the contact section 31 has a depth suflicient to permit considerable relative longitudinal movement between the sections 35 and 31 prior to disengagement of the contact fingers $5 from the inner surface of the cup-shaped portion 19. Thus during the opening operation of the interrupter following initial movement to the open circuit position by the operating mechanism 53, the sections 35 and 31 are maintained in electrical contact even though there may exist a tendency for these sections to separate prior to extinction of the arc drawn between the contacts 23 and 39. 'I'he tendency for the sections 35 and 31 to separate at the outset of the opening operation is due to unequal rates of acceleration of these two sections. The section 31 is pivotally coupled to the operating mechanism 53 and may start its opening movement with a relatively high acceleration due to the sudden application of force made possible by slack inherently in the operating mechanism linkage, whereas the section 35 is accelerated more uniformly by the springs 5| and does not receive the benent of slack in the operating mechanism.

From Figs. 2 and 3, it also clearly appears that the cap member 13 carried by the lower end of the stem 59 coacts with the cup-shaped portion 18 so as to form a dashpot for cushioning the impact of the member 31 with the member 35 during the closing stroke of the interrupter. The inner surface adjacent the open end of the cupshaped portion 19 is tapered, as shown at 8|, and the side walls of the cap member 13 are also tapered so as to provide considerable clearance between the cap member 13 and the entrance of the cup-shaped portion 19 to permit liquid to escape more freely from the cup-shaped portion 19 at the beginning of the shock absorbing action.

As the cup-shaped portion 19 is moved upwardly, the clearances become less and greater resistance to relative movement between the cap member 13 and the portion 19 is encountered. Thus the cap member 13 is finally brought into engagement with the bottom surface of the cupshaped member 19 without imparting shock or injury to the operating mechanism 53 or the contact structure.

As evidenced in Fig. 3, the contact fingers 65, the cap member 13 and the open end of the cupshaped portion 19 present smooth contours so that when the sections 35 and 31 are separated an even distribution of electric stress is obtained in the gap between the sections 35 and 31, which prevents the formation of corona and permits the gap to withstand a higher voltage. By making the sections 35 and 31 of equal diameter and arranging the contact fingers 65 to bear outwardly against the inner surfaces of the hollow end portions in the sections 35 and 31, a smooth external contour of these sections is maintained which permits free movement of the sections through the arc extinguishing unit I3. 'Ihis particular arrangement permits considerable saving in space in that the total height of the interrupter housing is thereby correspondingly reduced.

Although we have shown and described a particular contact structure for circuit interrupters of a given type, it is to be understood that the same is for the purpose of illustration and that the contact structure described as well as changes and modifications thereof may be employed in circuit interrupters of various types, as for instance, those employing grounded metal tank structures, without departing from the spirit and Vscope of the appended claims.

We claim as our invention:

1. In a circuit interrupter, stationary contact means, a movable contact piece coacting with said contact means to establish an are when moved to the open circuit position, operating means releasably coupled to said contact piece for actuating said contact piece to the closed circuit position, and dashpot means for cushioning at least the initial engagement of said operating means with said contact piece during the closing operation of said interrupter.

2. In a circuit interrupter, stationary contact means, a movable contact piece coacting therewith, means for operating said contact piece to the open circuit position to establish an arc between said contact means and said contact piece, operating means for operating said contact piece to the closed circuit position, said last named operating means being releasable from said contact piece when said contact piece is in the open circuit position, and dashpot means operative to cushion at least the initial engagement of said last named operating means with said contact piece during the closing operation of the interrupter. i

3. In a circuit interrupter, stationary contact means, a movable contact piece coacting therewith, energy storing means for operating said contact piece to the open circuit position, operating means for moving said contact piece to the closed circuit position and storing energy in said energy storing means, said `operating means including an operating member having releasable engagement with said contact piece, said operating member being disengaged from said contact piece when said interrupter is in the open circuit position, and shock absorbing means including a coacting male piston member and a female cylinder member carried'respectively by said contact piece and said operating member for cushioning at least the initial engagement of said operating member with said contact piece during the closing operation of the interrupter.

4. In a circuit interrupter, a pair of line terminals, stationary contact means connected to one of said line terminals, a movable contact member connected to the other of said line terminals, a movable contact piece coacting with said stationary contact means-and having releasable engagement with said contact member, operating means engaging said movable contact member for actuating the interrupter to open and closed positions, said contact piece beingl movable with said contact member during the initial opening movement of said operating means to establish an arc with said stationary contact means and being stationary during the latter portion of movement of said operating means to cause said contact member to disengage from said contact piece, and dashpot means associated with said contact member and said contact piece to provide at least an initial cushioned engagement of said contact member with said contact piece during the closing movement of said operating means.

5. In a circuit interrupter, stationary contact means, a movable contact member, an intermediate contact member normally interconnecting said stationary contact means and said movable contact member, operating means operatively engaging said movable contact member for actuating the interrupter to open and closed positions, slidably releasable contact means for holding said movable contact member in engagement with said intermediate contact member during at least the initial opening movement of the interrupter, means for arresting movement of said intermediate contact member during the latter part of the opening movement to cause said movable contact to disengage from said intermediate contact member, and shock absorbing means including coacting male and female piston and cylinder members carried by said contact members for cushioning the engagement of said contact members during the closing operation of the interv rupter.

6. In a circuit interrupter, stationaryr contact A means, a coacting movable contact member having two sections, releasable contact means joining said sections, actuating means operative to first institute a circuit interrupting break between one of said sections and said stationary contact means and thereafter to separate said sections to provide a disconnect break, said actuating means being operative to close the interrupter by first bringing said movable sections into engagement and finally moving said contact member into engagement with said stationary contact means,

and shock absorbing means including a recess in one of said sections and a piston carried by the other of said sections operative in said recess to cushion the engagement of said sections during the closing operation of the interrupter.

7. In a circuit interrupter, a plurality of relatively movable contact members arranged to form a plurality of breaks-in series, operating means for actuating at least one of said contact members to form an isolating break, said operating means being operative to actuate said one contact member into engagement with an adjacent contact member to close said isolating break and to thereafter close the remaining break, and shock absorbing means carried by said contact members forming said isolating break to cushion the initial engagement of said members during the closing operation of the lnterrupter.

8. In a circuit interrupter, a plurality of relatively movable contact members arranged to form a plurality of breaks in series, operating means for actuating at least one of said contact members to form an isolating break, said operating means being operative to actuate said one contact member into engagement with an adjacent contact member to close said isolating break and to thereafter close the remaining break, and dashpot means associated with said contact members forming said isolating break to cushion the initial engagement of said members during the closing operation of the interrupter.

9. In a circuit interrupter, arc extinguishing liquid, an arc extinguishing chamber immersed in said liquid, relatively movable contact structure within said chamber, a movable switch member exteriorly of said chamber in series with said contact structure within said chamber and operable in said liquid for controlling said contact structure, movement of said switch member to open circuit position causing initially separation of said contact structure Within said chamber to interrupt the circuit and subsequently separation of said switch member from said contact structure to form an isolating break, said movable switch member having a recess therein, and a plunger carried by said contact structure operative in said recess to cushion the shock occasioned by the closing movement of said switch member.

10. In a circuit interrupter, relatively movable contact structure for forming at least one interrupting break in the circuit to be interrupted, a contact member in series with said contact structure movable to control said contact structure and to form an isolating break with said structure upon movement to the open circuit position, said contact member having a cup-shaped recess adjacent one end thereof, a plurality of outwardly biased contact fingers carried by said contact structure adapted to engage the inner surface of said recess when the isolating break is closed, and a plunger secured to said contact structure operative in said recess to cushion the closing thrust of said contact member against said contact structure.

11. In a circuit interrupter, relatively movable contact structure for forming at least one interrupting break and an isolating break in series, said Contact structure including a pair of relatively movable contact members for forming said isolating break, a plurality of contact fingers pivotally supported at one end of one of said contact members, the other contact member having a cup-shaped portion at one end thereof for receiving said contact ngers, and means for biusing said contact ngers outwardly into engagement with the inner surface of said cup-shaped portion and said pivotal supports to normally provide a high pressure bridging contact between said contact members, said pair of relatively movable contact members having substantially the same shape to provide substantial external surface continuity along said members when said members are in engagement with each other.

l2. In a circuit interrupter, relatively movable contact structure for forming at least one interrupting break and an isolating break in series, said contact structure including a pair of relatively movable contact members for forming said isolating break, a plurality of contact fingers pivotally supported at one end of one of said contact members, the other contact member having a cup-shaped portion at one end thereof for receiving said contact iingers, means for biasing said contact lingers outwardly into engagement with the inner surface of said cup-shaped portion and said pivotal supports to normally provide a high pressure bridging contact between l a movable contact member coacting with said contact means, said contact member comprising two coaxial separable sections, at least a portion of both sections being within said arc chamber when the interrupter is in the closed position, means operating said contact member to open circuit position to establish a circuit interrupting arc in said chamber between said contact means and one of said sections and subsequently separate said sections to establish an isolating break outside said chamber, one of said sections having a hollow portion at the end thereof adjacent said isolating break, and a plunger carried by the other section operative in said hollow portion to cushion the shock of engagement of said sectionsduring movement of said sections to the closed circuit position.

14. In a circuit interrupter, an arc chamber, stationary contact means in said arc chamber, a movable contact member coacting with said contact means, said contact member comprising two coaxial separable sections, at least a portion of both sections being within said arc chamber when the interrupter is in the closed position, means operating said contact member to open circuit position to establish a circuit interrupting arc in said chamber between said contact means and one of said sections and subsequently separate said sections to establish an isolating break outside said chamber, the opposed ends of said sections having hollow portions thereon, a plurality of contact fingers yieldingly supported at one end Within the hollow portion of one of said sections and having portions thereof .extending from said hollow portion adapted to be received by the hollow portion of the other section when said sections are in closed circuit position, and spring means biasing said contact fingers outwardly to provide a high pressure Contact with the inne;l surfaces of both of said hollow portions.

15. In a circuit interrupter, an arc chamber, stationary contact means in said arc chamber, a movable contact member coacting with said contact means, said contact member comprising two coaxial separable sections, at least a portion of both sections being wthin said arc chamber when the interrupter is in the closed position, means operating said contact member to open circuit position to establish a circuit interrupting arc in said chamber between said contact means and one of said sections and subsequently separate said sections to establish an isolating Abreak outside said chamber, the opposed ends of said sections having hollow portions thereon, a plurality of contact fingers yieldingly supported at one end within the hollow portion of one of said sections and having portions thereof extending from said hollow portion adapted to be received by the hollow portion of the other section when said sections are in closed circuit position. spring means biasing said contact lingers outwardly to provide a high pressure contact with the inner surfaces of both of said hollow portions, and a plunger carried by said one section adjacent the free ends of said contact fingers, said plunger being operative in the hollow portion of said other section to provide a dashpot action for cushioning the impact of said sections with each other during the closing operation of the interrupter.

16. In a circuit interrupter, relatively movable l contact structure comprising a pair of coaxially arranged separable contactmembers, the opposed ends of said contact members having cup-shaped portions thereon, a stem extending coaxially of one of said members from its cup-shaped portion, said one cup-shaped portion having an annular groove in the inner surface thereof, a plurality of contact fingers disposed about said stem, each of said fingers having a lateral projection at one end thereof extending into said groove, the other ends of said fingers extending beyond said one cupshaped portion and being adapted to be received by the cup-shaped portion of the other contact member when said contact members are in the closed circuit position, spring members disposed between said contact fingers and said stem for biasing said contact fingers outwardly to provide high pressure contact with the inner surfaces of both cup-shaped portions, and guide means carried by said stem for yieldingly holding said contact lingers in predetermined spaced position with respect to each other.

17. In a circuit interrupter, an arc chamber, stationary contact means in said arc chamber, a movable vcontact member coacting with said contact means, said contact. member comprising two separable sections at least a portion of both sections being within said arc chamber when the interrupter is in the, closed position, means operating said contact member to open circuit position to establish a circuit interrupting arc in said chamber between said contact means and one of said sections and subsequently separate said sections to establish an isolating break outside said chamber, and dashpot shock absorbing meanstions being within said arc chamber when the interf rupter is in the closed position, means operating said contact member to open circuit position to establish a circuit interrupting arc in said chamber between said contact means and one of said sections and subsequently separate said sections to establish an isolating break outside said chamber, and dashpot shock absorbing means ycarried by said separable 'sections operative during the closing operation of the interrupter for cushioning the engagement of said separablesections. said dashpot shock absorbing means including a male piston member and a female cylinder member arranged to coact with each other to bring said separable sections into axial alignment when said interrupter is actuated to the closed circuit position.

19. In a circuit interrupter, a plurality of relatively movable contact members arranged to-form a plurality of breaks in series, operating means for actuating at least one of said contact members to form an isolating break, said operating means being operative to actuate said one contact member into engagement with an adjacent contact member to close said isolating break and to thereafter close the remaining breaks, and means for cushioning the engagement of said contact members forming said isolating break during the closing operation of said interrupter, said last named means including a piston and cylinder operative to bring said contact members forming said isolating break into predetermined alignment with respect to each other during the closing movement of the interrupter.

20. In a circuit interrupter, relatively movable contact structure comprising a pair of separable contact members, a plurality of contact fingers yieldingly supported from one end of one of said contact members, the other contact member having a hollow end portion for receiving said contact fingers, means for biasing said contact fingers outwardly into engagement with the inner surface of said hollow end portion to normally provide a bridging contact between said contact members, and a plunger carried by said one contact member operative in said hollow end portion of the other contact member to cushion the engagement of said contact members during movement thereof to the contact engaging position.

21. In a circuit interrupter, relatively movable contact structure-comprising a. pair of separable contact members, a plurality of contact lingers yieldingly supported from one end of one of said contact members, the other contact member having a hollow end portion for receiving said contact fingers, means for biasing said contact ngers outwardly into engagement with the inner surface of said hollow end portion to normally provide a bridging contact between said contact members, and a plunger carried by said one contact member adjacent the free ends of said contact fingers operative in said hollow end portion to provide a dashpot action for cushioning the impact of said contact members during movement thereof to the contact engaging position, the inner side walls of said hollow end portion tapering outwardly in a direction toward the open end thereof to provide progressively less clearance between said plunger and said side walls as the plunger is moved into said hollow end portion whereby said plunger coacts with said hollow end portion to bring said contact members into alignment.

ROSWELL C. VAN SICKLE. ERIK H. HALL. 

